Radio signaling system



June 5, 1.928. 1,672,027

I H. E. HALLBORG RADIO S IGNALING SYSTEM Filed July 24, 1925 2 Sheets- Sheet 1 a-rwenfoz 6 Henry E. Hwllborq June 5, 1928. 1,672,027

H. E. HALLBORG RADIO SIGNALING SYSTEM Filed July 24, 1923 '2 Sheets-Sheet 2 gwvvmtoz Henry E. Hallbory 35 L A 0 m1, 0 1000 A 2000 A .3000 A 4000 1 5000A k OBSERVED WAVES attonwq wo'nnms WAVE Patented June 5, 1928.

UNITED ST TES HENRY E. HALLBORG, or WASHINGTON, n-isrni'o'r or coLUMri-iA.

RADIO "SIGNALING SYSTEM.-

Application filed July 24,

My invention relates broadly to radio transmission circuits, and more particularly to a transmitting circuit utilizing the are or like generator of sustained oscillations.

One of the objects of my invention is to provide a signaling circuit which eliminates the compensation wave ordinarily radiated by a high power are transmitter.

Another object of the invention is to provide a circuit arrangement for an are or like generator whereby only the fundamentalv working wave frequency is radiated by the antenna system and mush and harmonics eliminated.

Another object of the invention is to provide a coupled circuit arrangement whereby the generator is inductively connected with the antenna system instead of being directly in the antenna circuit as heretofore employed.

A still further object of the invention is to provide a keying system for uniwavesignalin'g capable of high speed operation wherein steady operation of the generator is insured during signaling with substantially no fluctuation of power in the generator circuit during signaling.

My invention will be .more fully understood by reference to the accompanying drawings, in which:

Figure 1 is an elemental diagram representing a coupled arc transmitting circuit and the connections of the signaling keys in the primary oscillating circuit and in shunt with the primary coupling coil; Fig. 2 is a diagram of an arc transmitting circuit wherein the signaling keys are placed in the primary oscillating circuit and in shunt with the secondary coupling coil; Fig. 3 shows a modified circuit arrangement withmeans for changing the reactance between the primary oscillating circuit and the antenna circuit when keying to a sufficient amount to prevent leakage of energy from the primary oscillating circuit into the antenna circuit when itis desired that it should be excluded therefrom whereby the antenna circuit is less likely to have any residual current therein during space intervals between signals; Fig. 4 shows the application of my double by-pass circuits connected with an arc transmitting circuit functioning with the coupled circuits for suppressing the radiation of harmonics from the antenna system; and Fig. 5 is a chart showing observations taken with a receiver on different wave 1923 Serial No. 653,493.

the number of listening. in stations which have followed the installation of broadcasting stations.

In my present invention I provide a coupled are or like generator circuit which eliminates mush and harmonics, and to further exclude harmonic-s I provide by-pass circuits in the primary coupled circuit having high reactances for the fundamental frequency and-low reactancefor harmonic frequencies. In transmitting the signals a key is placed in' shunt with the primary coupling coil or the secondary coupling coil, and a key is also placed in the primary oscillating circuit in shunt with an absorbing circuit and the keys alternately operated to produce thesignal. No fi'ne adjustment to insure overlap condition is necessary as is? the case in keying other types of circuits.

Referring more particularly to the drawings, Fig. 1 shows'on'e arrangement for keying the coupled circuit. Reference character 1 represents the direct current power circuit which supplies the are 2. The are is provided with an arc field 3, which may be either self or separately excited. The field is preferably separately excited in order to take full advantage of the reduction in mush and harmonics by the medium of the loose coupled circuit hereinafter described and the accurate adjustment of the arc transverse field strength. -Reference characters 4 and 5 represent respectively the capacity and'inductance of the primary circuit, capacity 4 being so selected as to cause the arc 2 to work at relatively high supply voltage where its efficiency as a converter is the greatest. Reference character 6 denotes the primary of the antenna coupling coils coupledwith theseconolary' 7 connected in the antenna circuit. The antenna circuit comprises antenna 8, antenna loading coil 9, radiation amineter 10 and ground or counterpoise 11. The primary coupling coil 6 is shunted by a short circuiting key 12 made up of a plurality of contacts each arranged to short circuit only a portion of the total coil 6 in order to reduce sparking at the contacts. The coil 6 may also be shunted by a resistance without reducing the antenna input when key 12 is open,

although this resistance is not necessary under normal circumstances except in high power arcs. Reference character 14 shows a balance resistance absorbing the equivalent of the energy input to the antenna when inserted in the primary circuit by opening of its shunting key 'or plurality of keys 15. The primary. circuit is grounded at 16.

The sparking at the contacts of key 12 across the turns of the primary coupling coil 6 may be reduced to negligible value by connecting the key in shunt with the secondary coupling coil 7 as indicated by reference character 18 in Fig. 2. One side of each of the sets of keys-15 and 18 is always at ground potential in this circuit and, therefore, safe to touch during keying. A variometer 19 is connected in the antenna circuit for ad justing the frequency of the circuit in line degrees. The electromagnets which control the keys 15 and 18 are so connected that keys 15 open when keys 18 close, and vice versa.

The circuits described herein are the result of extensive investigations with high power are transmitters. The circuits have been found to be particularly adapted to high power are transmitters due to the exact balance of power obtainable between signal and no signal positions. This uniwave system permits as steady operation of the are as the existing double wave or compensation systems. It is not necessary that keys l5 and 18 overlap with any degree of precision, for with the present circuits the arc is steady even under the condition of much power unbalance. Keys 15 and 18 may be combined in one key or may be two separate units as represented in the drawings.

Five functions are performed by keys 15 and 18 as follows:

Key Signal position No signal position 15 Cuts out of circuit balancing resistance 14.

Balances power input by cutting 1n antenna balancing resistance Lengthens wave of primary. Removes driving voltage from antenna.

Shortens wave of antenna.

15 Shortens wave of primary. 18 Applies driving voltage to antenna. 18 Tunes antenna to Wave of primary. 18 Provides maximum cou- Provides minimum coupling to pling to antenna.

antenna.

inductance 9, but this may not be practicable. In order to avoid inherent coupling I may provide an inductance 24 which is placed in series with resistance 25 and shunted by key 26 in the primary circuit. The inductance 24 is of such value as to throw the primary and secondary circuits out of resonance by changing reactance'up on operation of key 26. The reactance change when keying becomes sufficiently great that leakage into the antenna is prevented. By use of this additional inductance 2 1 the antenna circuit is less likely to have any residual currents therein between signals.

While the coupled circuit eliminates undesired harmonics to a considerable degree, I- may provide a double by-pass circuit, as rep,- resented in Fig. 4, to more completely eliminate from the antenna system all frequencies except the working wave. The by-pass circuits are indicated at 27 and 28 comprisin low reactance paths for harmonics, and high reactance paths for the fundamental or working wave. The paths include inductance 29 and capacities 30 and 31, am{ meters 32 and 33 being placed in each of the Icy-pass circuits to determine the relative conditions thereof.

The ammeter' 23 indicates the total current in the primary oscillating circuit, while the ammeters 32 and 33 indicate the current in the circuits having low reactance for har monies. In a series of observations this circuit arrangement has been found extremely effective in eliminating the radiation of barmonics. I

Fig. 5 is an audibility chart preparted by taking observations at a distance of 2.6 miles from the arc transmitter, employing a two wire antenna and two stages of audio fre quency amplification. The working wave audibility is indicated by the vertical curve 3 1. The only harmonic to be observed after searching over. the range indicated by the absc'issae was one of extremely slight audibility indicated at 35. In other are signaling circuits harmonics exist at frequent intervals throughout the range indicated and cause considerable interference around the broadcasting range.

The theory of operation of the invention is as follows :In the signal position Fig. 1,

key 12 is open and 15 is closed. The antenna is energized by transfer of energy from the primary circuit to the secondary circuit by means of coupling coils 6 and 7. The wave lengths of the primary and sec ondary circuits are equal and a maximum of energy flows to the antenna. In the nonsignal position key 12 is closed. The antenna energy drops to zero due to thefact that the antenna driving voltage has been reduced to Zero by short circuiting the coupling coil 6 and to the additional fact that the primary circuit wave has been shortened ke 1 contacts becomes ne li ible and b rea-' son of the fact that one side of both sets of keys is at ground potential'they are safe to touch during keying.

The operation of the circuit diagrams in Figs. 3 and 4 is similar tothe circuits heretofore described. Contrary to expectations,

the coupled arc is not the same .as the Well known coupledspark circuit. In spark sets a relatively small inductance and large capacity is required for the circuits, whereas.in coupling the arc with the antenna inductive- 1y by removing the usual conductive connection with the antenna the circuits requlrea relatively large inductance.

By my arrangement of coupled circuit, keying system, and double by-pass circuits, the arc becomes as eflicienta form of transmitterother things considered-as can be desired when compared to other forms of transmitters available for-radio signaling.

lVhile I have described my invention in certain specific embodiments and with particular reference to an arc generator of sustained oscillations, it is to be understood that modifications may be made within the scope of the appended claims without departing from the spirit of my invention.

Having thus described my invention,'what I claim and desire to secure by Letters Patent of the United States is as follows:

1. A radiotransmitting system, comprising in combination an antenna system, means for generating sustained oscillations, a primary oscillating circuit connected with said means, a primary coupling coil connected in said circuit, a secondary coupling coil connected with said antenna system and inductively coupled with said primary coupling coil, and a plurality of sets of signaling keys, one of said sets of keys being connected in shunt wit-h said primary coupling coil and another of saidsets of keysbeing connected in series with said primary oscillating circuit and in parallel with a resistance arranged to absorb the energy normally radiated by said antenna system when said keys in shunt with said resistance are opened.

2; A radio transmitting system, comprising in combination an antenna system,

' means for generating sustained oscillations,

a primary oscillating circuit connected with said means, a primary coupling-coil con-- nected in said circuit, a secondary coupling coil connected with said antenna system and inductively coupled with said primary couwhereby ener pling coil, and a plurality of sets of signaling keys, one of said sets of keys being connected in shunt with the primary coupling coil, and another ofsaid sets of keys being connected in series with said primary oscillating circuit and in arallelwith resistance.

3 A radio transmitting system compris ing'in combination an'antenna system, means for generating sustained oscillations, a primary oscillating circuit connected with said means, a primary-coupling 0011 connected in said circuit, a secondary coupling coil connected with said antenna system and inductively coupled with said primary couplingcoil forming a coupled system, and a plurality of sets of signaling keys, one of said sets of signaling keys being connected in shunt with the primary coupling coil and the other of said sets of signaling keys be- I i ing connected in shunt with an absorbing resistance and in serles with said primary osc llating circuit, said signaling keys being arranged so that one set is open while the other set is closed for transmitting a signal is radiated by said antenna only during signaling intervals.

Y 4. In a high frequency electric circuit, the combination of a source of power, a resonant circuit coupled thereto; said resonant circuit including an inductance, acoupling coil and a resistance in series with each other; and

means for alternately rendering the coupling coil and the resistance inoperative, said means consisting of a single multicontact key,said key consisting of a plurality of pairs of contacts, one pair of contacts connected to the terminals of the resistance,'another pair of contacts connected to the terminals of the coupling coil and means for alternately opening and closing each pairof contacts.

. 5. In a high frequency electric circuit, the combination of a source of power, a resonant circuit coupled thereto; said resonant circuit including an inductance, a coupling coil and a resistance in series with each other; and means for alternately rendering the coupling coil and the resistance inoperative, said means consisting of a single multicontact key, said key consisting of a plurality of pairs of contacts, one pair of contacts connected to the terminals of the. resistance, an-

other pair of contacts connected to the terminals of the coupling coil and means for alternately opening and closing each pair of contacts, said means consisting of a lever pivoted about a point centrally disposed with respect to the pairs of contacts, a plurality of conducting members mounted upon the lever andarrangedto alternately close the pairs of contactsas the lever is moved about its pivot.

HENRY E. "HALLBORG. 

